A hydrodynamic heater generates heat by inducing shear within a fluid. The shear may come in the form of structure that is caused to move within the fluid. Heat may be generated by a principle known as fluid resistance heating, in affect, friction heating. Heating may also be generated by a principle of direct cavitation within layers of liquid. Although the transformation of mechanical energy into thermal energy via the hydrodynamic heater is relatively efficient, an increase in energy efficiency is desirable.